Antarctica Glossary
of terms I - Z

ice age
(glacial period) - Periods in the Earth's history when the climate
was colder and glaciers expanded to cover large areas of the Earth's
surface. Ice ages have come and gone many times and will probably continue
to do so.

ice blink - A brightness
on the horizon, showing in the clouds above it caused by reflection
of sunlight from sea ice even in overcast conditions, such a sight is
often called an "ice sky". Conversely, a darkness on the horizon
when surrounded by ice denotes the presence of open water and is called
a "water sky".

ice cap - A large dome-shaped
mass of ice that is thick enough to cover all the landscape beneath
it so appearing as a smooth coating of ice. Ice caps are smaller than
ice sheets, usually under 50,000 square kilometres (19,000 square miles).
Ice caps can deform and flow with gravity and spread outward in all
directions. Freshwater.

ice cliff - Walls of ice
where glaciers meet the sea. Ice cliffs occur because icebergs calve
from the front of them giving a continually breaking edge the full height
of the glacier. Freshwater.

ice crystals -
Tiny particles of ice that grow on all surfaces when the air is supersaturated
with water (cold air doesn't hold much moisture so ice crystals
are readily formed in Antarctica). Ice crystals account for the majority
of the accumulation of glacial ice on the Polar Plateau. They may also
be referred to as ice needles, even though they are not needle shaped.
Freshwater.

ice floe - A large,
flat, sheet of sea ice that has broken off contact with the coast where
it was formed and is floating in open water. Sea-water.

ice foot - A "shelf"
of ice that forms around many Antarctic shores in the winter time. Sometimes
formed by sea spray, often formed where sea-ice joins the land, as the
tide rises and falls, a layer of ice is deposited which builds up. Once
the sea ice blows out in the spring a distinct ledge several feet high
is left behind that can be difficult to cross for men and also for animals.
Sea-water

ice sheet - A large mass of ice that
is thick enough to cover the landscape beneath it so appearing as a
smooth coating of ice. Ice sheets can deform and move with gravity,
they are larger than ice caps. Ice sheets cover much of Greenland and
Antarctica. Freshwater.

ice shelf - A large flat-topped
sheet of ice that is attached to land along one side and floats in the
sea or a lake. Formed where a glacier or ice shelf has reached the water
and kept flowing, it is fed from the landward side and eroded from the
seaward side by the calving of icebergs and melting. Freshwater.

ice stream - A rapidly moving current of ice in an ice
sheet or ice cap. Ice streams flow more quickly than the surrounding
ice and remove ice from the ice sheet. Antarctic ice streams may flow
about one kilometre per year (0.6 miles per year). Freshwater.

ice tongue - A
long, narrow, projection of ice out from the coastline, similar in origin
to an ice shelf, but usually formed where a valley glacier flows rapidly
to the sea or a lake. Freshwater.

iceberg - A large
piece of floating ice that has calved, or broken off, a glacier or ice
shelf. Icebergs occur in lakes and the ocean and can be vast, the size
of islands or small countries. Freshwater.

ionosphere
- The electrically-charged layer of the atmosphere that extends from
80 to 400 kilometres (50 to 250 miles) above the Earth's surface.
The ionosphere absorbs much of the short wave-length radiation from
the sun. As the radiation passes through the ionosphere, it interacts
with nitrogen molecules and oxygen atoms. These molecules and atoms
absorb the radiation, but in the process they lose an electron (a negatively
charged particle) and become a positively charged ion. The ionosphere
is where auroras originate.

katabatic winds
- Wind that results from dense, cold air flowing down a slope by gravity.
Over Antarctica, air cools over the high plateau region and flows towards
the coast, by the time it gets to the coast it can have reached extreme
speeds and blow continuously for weeks.

land-based ice sheet
- a large body of ice with a base mostly above sea level. The East Antarctic
Ice Sheet is a land-based ice sheet. Freshwater.

lapse rate - The
change in temperature associated with a change in elevation. When climbing
a mountain, the temperature falls approximately 1°C for every 100m
in altitude gained.

latitude
- Imaginary lines that allow for the measurement of position north or
south of the equator. Latitude is measured in degrees (one degree -
60 nautical miles, or 111 kilometres). The equator is at a latitude
of 0° and the poles lie at latitudes of 90° north (North Pole)
or 90° south (South Pole). Lines of latitude differ in length according
to how far north and south they are.

lead - Long, narrow
opening or fracture in sea ice. Leads can be useful to shipping because
they do not have to waste fuel and time by breaking ice, they can be
disastrous if travelling over sea-ice as the path is no longer there.
Leads are also useful to seals and whales that can use them to breathe
and for birds that can feed on marine prey through the lead.

lichen - Symbiotic association of alga and fungus. The fungus
provides protection and moisture, the photosynthetic algae provide food
for the fungus. Lichens are the toughest form of plant life and can
live in some of the coldest and most exposed places in Antarctica as
long as they have a rock to cling to. They can actively grow and photosynthesize
at well below freezing point - albeit very slowly.

limnology
- The study of freshwater such as lakes, ponds, and marshes. The analysis
of the physical and chemical characteristics of the freshwater as well
as the plants and animals that live within them. Antarctic lakes are
more affected by climatic and other changes than is the ocean and so
they are seen as giving an early warning of any impending changes.

longitude - Imaginary lines that wrap around the Earth intersecting
at the north and south geographic poles. Lines of longitude are numbered
from 0° (the Greenwich Meridian, passing through Greenwich in London,
England) to 180°. Longitudes are called east if they fall east of
the Greenwich Meridian, and west if they fall west of the Greenwich
Meridian. Lines of longitude are all of the same length.

magnetic storm
- Times when the sun radiates large amounts of ions and electromagnetic
energy out towards the solar system, tied to sunspot activity. This
influx of high energy disturbs the Earth's magnetic field causing
interruptions to telecommunications broadcasts and particularly pretty
auroras.

marine biology - The study of plants and animals
living in the seas and oceans.

maritime - Bordering
or next to the ocean or sea. Maritime climates are oceanic climates,
and are milder than the inland climates because of the moderating influence
of the sea which acts as a huge heat sink absorbing heat in the summer
and giving it out in the winter.

meteorology - The study
of the Earth's atmosphere and the movements of air and moisture
within the atmosphere. Includes the study of the atmosphere for weather
forecasting.

meteorite - Fragments of rock that reach
the Earth from beyond the atmosphere. Most are believed to come from
asteroids, some are believed to be pieces from other planets. Antarctica
is a particularly good place to find meteorites as they show up against
the snow and ice and are accumulated in some places by the flow patterns
of ice streams and glaciers.

migrate - Moving from one
area to another. Some animals migrate in certain seasons to find better
conditions, such as weather, food, or for breeding. Many whales migrate
to the Southern Ocean in the summer to feed on the large the quantities
of krill for example.

moss - Small, leafy-stemmed
plants that grow in carpet-like mats and tufts on moist ground. Particularly
abundant in maritime regions of Antarctica where conditions are too
harsh for other types of plant. In Antarctica mosses often accumulate
in large "moss banks".

nekton - Free-swimming
aquatic animals that move under their own power and can move independently
of ocean currents. Whales, squid and many fish are types of nekton.

niche - The life style of an organism, its "job"
also - the place in which it lives, what it eats, how it gets nutrients,
and the interplay it has with the environment and other organisms.

nip / nipped
- a dreaded description of a ship from the early days of polar exploration
when she was trapped by ice on both sides that was pushing in hard.
In contrast to the gentle sounding nature of the event, the reality
was often that the ship suffered considerable damage or was broken and
sunk.

nunatak - An isolated peak of bedrock that sticks
above the surface of an ice sheet. They are the peaks of hills and mountains
standing above the ice sheet which flows around them. They offer important
information about ice covered regions as they provide a sample of the
rocks that lie under the ice.

oceanography -
The study of the ocean. The physical properties of the ocean - currents
and waves (physical oceanography), the chemistry of the ocean (chemical
oceanography), the geology of the seafloor (marine geology), and the
organisms that live in the oceans (marine biology and marine ecology).

ordinary katabatic wind - Short-lived katabatic winds with
constant direction but a highly variable speed. Originate in cold dense
air flowing coastward from the high Antarctic plateau over the pole.

ozone layer - A
layer in the Earth's upper atmosphere, the stratosphere that contains
almost 90% of the Earth's ozone. This forms a protective blanket
against the harmful ultra-violet rays coming form the sun.

pack ice - Often
used interchangeably with sea ice. Pack ice is frozen sea that formed
somewhere else and has floated to its present position carried by wind,
tides and currents. It is broken up and of variable size and thickness,
some pieces can be the size of a coffee table and about 1 foot (30cm)
thick, other pieces are larger than a tennis court and can be 30ft (9m)
or more thick. Usually pack ice is in its second season. Sea-water

Open
pack - when the pieces of ice don't touch
Closed pack - when the pieces of ice touch

pancake ice -
Pancake ice grows from thickened grease ice and resembles pancakes or
lily pads. The edges of each piece is upturned because the plates bump
into each other as they gently move around in the sea. Usually between
about about a foot (30cm) and 6 feet (2m) across. Pancakes tend to be
smaller the closer to the shore line they are. Sea-water

physical oceanography
- The study of the physical aspects of the seas and oceans such as the
temperature, salinity, density variation, and the optic and acoustic
properties of the ocean. Also includes the study of nature of currents,
waves, and tides.

phytoplankton - Plant plankton. Microscopic
free-swimming or suspended marine or freshwater plants within the plankton.
Plankton is defined as being those organisms that inhabit the upper
regions of a body of water, but cannot move about against the influence
of water movements such as currents, they move generally with the water
although may be able to move small distances. Phytoplankton includes
diatoms and other photosynthetic algae, a crucial part of almost all
aquatic food webs.

plate tectonics - A theory that ties
together many observations made about the activity and movement of Earth's
crust (earthquakes, volcanoes) and creation of ocean basins. Plate tectonics
divides the surface of the globe into a number of rigid plates that
move around the earth's surface over the period of millions of years.

polar - To do with
the regions of the north and or south poles of the planet. The poles
are cold, icy regions, a polar climate is a cold climate, with average
temperatures less than 10°C (50°F).

polar easterlies -
Winds that blow from the east as they flow off the high Antarctic
polar plateau. Polar easterlies help generate ocean surface currents
(east wind drift) in the Southern Ocean.

Polar Front (Antarctic
Convergence) - A surface boundary where which the colder, north
flowing Antarctic Surface Waters sink beneath warmer circulating waters.
This marks a change in the oceans surface temperature and also chemical
composition. North of the convergence, the area is known as the sub-Antarctic.

Polar Plateau - The relatively flat, high altitude central
region of the East Antarctic Ice Sheet. The plateau has an average height
of 2000 meters (about one mile) above sea level and a smooth surface
with a small slope towards the coast in all directions.

polynyas - A polynya
is an area of open water in pack ice or sea ice, they may be kept open
by constant winds or the upwelling of water and so tend to recur in
the same locations year after year. They are particularly important
for wildlife as they allow mammals such as whales and seals to have
a breathing hole and birds access to the sea in order to fish.

precipitation - Rain, snow, hail, sleet etc. moisture falling
from clouds to the surface of the Earth, usually as rain, snow, and
ice. The amount of precipitation is always measured as water or rain
equivalent so allowing for the fact that snow can have various structures
and densities

productivity
- A term used to describe the rate of production in an ecosystem.
Extra nutrients usually increase productivity.

reflectivity - The
amount of light or energy that bounces off a surface relative to the
amount of light or energy that reached the surface. A mirror is an example
of an object with high reflectivity. The ocean has low reflectivity.
Reflectivity may also be called albedo.

rookery - A colony
of rooks, the term is also used for a colony of penguins.

salinity
- The amount of dissolved salts contained in sea water. The average
salinity of sea water is 35 parts per thousand, but can vary with location.

sallying a ship
- from the early days of polar exploration, causing the ship to roll
by crew and passengers running from side to side to prevent adhesion
of the ice around her.

sastrugi - Irregular
ridges of snow on a small scale (rarely more than 1 foot, 30cm) that
lie parallel to the direction of the wind. Sastrugi can make travel
very awkward or difficult, they can be quite soft or as hard as ice.

sea ice - A general term for any ice that forms from frozen
seawater. Sea ice covers large parts of polar waters in the winter and
melts back each summer.

sleet - Frozen
or partially frozen rain that form when rain passes through a layer
of air that is below the freezing temperature, falls to earth as a slush.
Freshwater.

South geographic pole
- 90°S. The south geographic pole is the southern location where
the axis of rotation of Earth intersects Earth's surface.

South geomagnetic pole
- The point on Earth's surface in the Southern Hemisphere where
the axis of the Earth's magnetic pole intersects. The south geomagnetic
pole is approximately 1160 kilometres (725 miles) north of the south
geographic pole (think about it). The south geomagnetic pole is tilted
about 12 degrees to the axis of rotation of the Earth (geographic pole).

South magnetic pole - the point on Earth's surface that
a south-seeking compass needle seeks. At the South magnetic pole a compass
needle will point vertically downwards. This point is currently off
the coast of Wilkes Land and wanders around.

stratosphere
- The layer of the atmosphere that is above the troposphere, it extends
from approximately 10 to 50 kilometres (6 to 31 miles) above Earth's
surface. The upper region contains the ozone layer.

subglacial
- Underneath the glacier.

supercooled - A condition when
water is still liquid even though it is at a temperature at which it
normally would freeze. Often under these conditions a small physical
movement a small knock or tap will cause the water to freeze almost
immediately.

tabular iceberg - A
flat-topped iceberg, like a table. Freshwater.terrestrial - Dry land. Terrestrial
flora and fauna live on land not in water.

tide crack - Any
crack in sea ice that is caused by the rise and fall of the tide. As
the tide rises so the area of the sea increases and a crack forms, as
the tide falls, so the area decreases and the crack closes. Often form
around offshore rocks, between the shore and sea-ice, around grounded
ice bergs or even stretching for miles between islands.

tongue - A mass
of ice projecting from a glacier into the sea. It is still fixed to
and forms a part of the larger glacier. freshwater

trade winds
- One of three major circulation cells in both the northern and southern
hemispheres. The trade winds from approximately 0° to 30° north
or south latitude. Within the regions of the trade winds, prevailing
winds blow toward the west. They were given their name as in the days
of sailing ships, they aided the progress of the ships and hence the
trade of goods carried by those ships.

ultraviolet radiation
(UV) - A part of the electromagnetic spectrum that has shorter wavelengths
than visible light. Ultraviolet radiation has more energy than visible
light and can damage tissue (like human skin). Much of the ultraviolet
radiation from the sun is absorbed within the ozone layer before it
reaches the Earth's surface.

upper atmosphere physics
- The study of processes that take place in the upper atmosphere. Includes
study of the interactions between the various atmospheric gases and
cosmic radiation, such as the ozone layer.

upwelling -
An oceanographic term, the rising of deeper waters to replace surface
waters. Upwelling often brings waters rich in nutrients to the surface,
resulting in a region where ocean productivity is high.

West Wind
Drift (Antarctic Circumpolar Current) - A Southern Ocean surface
current flowing east and driven by westerly winds. The West Wind Drift
carries a large volume of water and it is a strong current because no
continents are in the way of the flow path.

white-out - A weather
condition in which the horizon cannot be identified and there are no
shadows. The clouds in the sky and the white snow on the ground blend
- described as like walking along inside a ping-pong ball. White out
conditions are potentially dangerous because it is difficult to find
a point of reference and it is very easy to walk over a cliff or fall
down a crevasse in such conditions.

wind chill - A way
of describing the temperature that takes into consideration the effect
of the wind speed in the temperature reported. Wind makes any temperature
feel colder and wind chill factor is a way of expressing how cold the
wind might make the temperature feel. First described after experiments
by the American scientist Paul Siple on baked bean cans containing water
and a thermometer left in the wind.

zooplankton -
Animal plankton. Microscopic free-swimming or suspended marine or
freshwater animals within the plankton. Plankton is defined as being
those organisms that inhabit the upper regions of a body of water,
but cannot move about against the influence of water movements such
as currents, they move generally with the water column although
may be able to move small distances. Many marine animals spend part
of their lives as zooplankton, often as a juvenile life stage. One
of the most important components of the Antarctic zooplankton is
krill.